Hot-blast stove



(No Model.)

2 Sheets-Sheet 1. J. M.,HARTMAN.

HOT BLAST STOVE.

No. 275,908. Patented Apr.1'7,1883.

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(No Model.)

2 Sheets-Sheet 2.

J. M. 'HARTMAN.

HOT BLAST STOVE.

Patented Apr. 17,1883.

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WITNESSES:

UNITED STAT-ES PATENT OFFICE.

JOHN M. HARTMAN, OF PHILADELPHIA, PENNSYLVANIA.

HOT- BLAST STOVE.

SPECIFICATION forming part of Letters Patent No. 275,908, dated April 17, 1883.

Application filed November 30, 1881.

To all whom "it may concern:

Be it known that I, JOHN M. HARTMAN, of the city of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Hot-Blast Ovens, of which the following is a specification.

This invention relates to hot-blast ovens, or

improved means for heating air or other gases; and it consists, first, in a new arrangement of foundation for regenerative stoves; second, in a new method of securing the roof of the stoves; third, in securing the coping-brick of the regenerators; fourth, in providing for the expansion of hot-blast pipe. I attain these objects by the means illustrated in the follow ing drawings, in which- Figure 1 is a plan of the stoves and chimney, the gas and chimney flues, and the central passage under the stoves. Fig. 2 is a front elevation of the stoves, showing the hotblast and steam pipe and thevertical part of the gas-flue, with capes in section. Fig. 3 is a sectional elevation through A B of Fig. 1, showing its interior arrangement of brick-work, the valve to control the gas, the foundations of the stoves, the combustiou-chamberj", regeneraa' ors ij, and back flue, 9. Fig.4 is a sectional view of the hot-blast pipe and disks. Fig. 5 is a sectional plan, showing in section the'cleaningdoor, parts of the regenerators t'j, part of the lining-wall h, part of the division-wall is, end 9 of division-wall, and open space It.

Similarletters refer to similarparts throughout the several views.

= Regenerative stoves are used to absorb heat from the gases passing through them and store it up to afterward heat a volume of air or gas passed through them. They consist of an air-tight iron shell which is filled with brick, having numerous vertical passages through it, in which the gas is burned and theheat absorbed from it. The stoves are connected with a chimney, f, which carries off the spent gas, and suitable valves are provided to control the blast, gas, and products of combustion or spent gas. When applied to blast-furnaces, the heat imparted to the blast blown through the stoves will cause a furnace to run faster, make more iron, and use less coal for the production of a ton of pig.

Heretot'ore the ashes and dust depositih g (No model.)

in the tines ab, Fig. 1, of regenerative stoves have been removed by the workman going into the flues and shoveling the dust out overhead through an opening in the top of the fines. As these flues get hot, they have to stand for some hours with the doors opened to allow them to cool before the Workman can enter. During this cooling the furnace remains idle, which causes a loss in the production of iron and irregularities in the working of the furnace. By placing a central passage, 0, under the stoves and placing cleaning-doors (l d d, 850., in the passage 0, with openings communicating to the fines a b, the dust and ashes can be-scraped out into the passage 0 at casting'time in a few minutes and without stopping the furnace for cleaning the flues.

In operating regenerative stoves the volume of gas is controlled by opening or closing par-.

tially the gasvalve c by hand. I prefer to open the gas-valve wide and control the volume of gas by the draft of the chimneyf. By placing on the gas-discharge side of the stove the valve g, counterbalanced with adjustable weights and to open inward, the valve will be drawn open by any excess of draft of the chimney over or above what the weights are adjustable to. When the valve is drawn open, the cold air isdrawn into the chimney, which increases the volume the chimney has to discharge, and at the same time cools the chimney and checks its draft. This valve regu lates the temperature of the chimney, and thereby an evenflow of gas of any desired quantityis obtained during the time the stoves are heating up.

. Heretofore the shell of the roofs of regenerative stoves, when formed of two arches, have the parts where the two arches meet riveted together. The curvature of the roof-shell ,forms a girder capable of resisting seven or eight pounds blast-pressure.

With the high pressures now blown--twenty pounds maximum--the roof must be made much stronger. By extending two sides of the stove-shells above the roof, as at l, insertin' g the girder m in the center, and securing the ends of the girders m to the extended sides 1 of the stove, the roof-shell is made sufficiently strong to resist the heavier pressure.

The gas used to heat these stoves is t'reighted with ashes and dust from the furnace, which, settling on the walls, prevent them from taking up or giving out their heat. Most of this dust is silicate of iron, which glazes on the walls and makes it difficult to remove. By inserting in the flue leading gas to the stove the annular slanting capes n n n, 860., the heavy dust-mostly silicates of iron-is removed, and with it the greater part of the light dust. The areas through these capes are so proportioned that the gas travels at the rate of about one foot per second in passing them. At this rate the particles of dust will lodge on the capes, and their friction on them will be suflicient to prevent the current carrying them along. The particles of dust will collect on the capes until they form a coating about one inch thick, when they slide off the capes, fall to the bottom of the flue, and are removed through the doors 0 0. By this means the heavy dust is kept out of the stoves, and they require to be cleaned less often. The dust and gas ashes settling on the walls of these stoves prevent the walls from absorbing or radiating heat, and require to be removed frequently.

In the English patent of Siemens Cowper Cochrane, No. 167,644, September 14, 1875, it is stated that the dust can be blown out ofthe stove with the blowing-engine by placing a door in the flue beyond the gas-valve. This door in the gas'flues being opened and the blowing-engine started, the cold blast is blown through the stove. This does not remove the dust from the regenerators, as the current through the large numbers of openings is too slow. If it is attempted to blow a large volume through the stove, the limited area of the gas-valve will increase the pressure in the stove beyond the power of the blowing-engine to force the volume through. By inserting a steam-pipe, p, in the front of the stoves, steam can be blown through them. The chimneyvalve g, which is five times the area of the gas-valve 6, having been opened and the cleaning-door s also, a large volume can pass swiftly through the stove without having its pressure increased by a restricted opening like the gas-valve.

To clean the stoves, I start the blowing-engine at a quick speed and blow the air through one stove, where it is heated-say 1,200 and pass it through the hot-blast pipe t into the stove to be cleaned, where it meets the jet of steam from the pipe p, which it immediately expands to about four times its original volume. This makes an enormous vol ume, that, rushing through the stove, sweeps out the dust and ashes and escapes through the chimney-valve and cleaning-door. By this means in a few minutes a stove can be thoroughly cleaned.

Suitable valves are placed in the steam-pipe p to control the volume of steam. The end of the steam-pipe 12 in the stoves has numerous holes in it to scatter the steam and prevent it impinging on the walls. The steam-pipep can be made sufficiently large to clean the stoves without the addition of air from the blowingengine. I

In removing the dust from a regenerative stove by a swift current of air or steam the top courses of the brick forming the coping of the regenerators are blown off. To prevent this I finish the top courses with an inverted arch, w, or a deep coping, which retains the brick in position.

Heretofore flat circular disks about onefourth inch thick have been used in the hotblast pipe to prevent the expansion of the pipe t t from breaking the connection zz z. These disks, by their great internal surface and the heavy pressures of blast now used, exert an end-thrust on the pipe and break the connections. The pipe t t, being lined with fire-brick, weighs about seven tons, and by its weight buckles the disks and causes the pipe to sag down. I make the pipe t with the disks (1., as heretofore, but leave one part of the pipe extend loosely into the other pipe, as at b, which prevents the pipe from sagging. I then rivet the tie-rod c to the pipe at d e, which leaves the pipe contract and expand between these points, but the end-thrust of the disks being resisted by the tie-rod thecon nections are not broken.

I am aware that two flues have been used in the foundations of regenerative stoves.

I am aware that weighted valves with no communication to the air have been used to control the flow of gas in fines.

I am aware that rectangular slanting capes have been used to catch dust; also that hollow cones having no central opening have been used to catch the products of distillation.

I am aware that H-girders have been used to stifien the flat wrought-iron roof-shells of flat-top regenerative stoves.

I am aware that it has been proposed to' clean the flues of regenerative stoves by blowing with a pipe a jet of steam down through each flue successively.

I am aware that hollow cones having a central opening have been used to deflect the sparks in a locomotive smoke-stack.

I claim 1. In combination with a regenerative stove, the foundation, as described, provided with passages forthe gas on one side and a passage for the products of combustion on the other side, and an archway intermediate thereto, and

intersecting passages connecting the same, as 7 set forth.

2. In combination with the flues of a hotblast oven, the valve G, constructed as described, whereby it may be opened automatically by the suction or draft and a current of cold air admitted to regulate the temperature of the stove, as described.

3. The combination of a regenerative stove with an air-tight iron casing or shell extended at'its sides, as described, the top or roof of IIO said shell, formed of two segments of plate-- iron, and the girder m secured at its ends to I to allow for the expansion of a pipe, the tie- 10 the sides of the shell and to the roof-plates, as rode, to prevent the spreading of the disks set forth. or the breaking of the connections by the end- 4, A regenerative stove having heatingthrust of the disks. walls of fire-brick, said walls having copings constructed in the form of inverted arches, as JOHN HARTMAN' described, to prevent the top bricks being Witnesses: blown oi1 by the force of blast, 85o. HARRY O. PHILLIPPE,

5. In combination with the flexible disks a, J. H. FRIES. 

